Devices and methods for controlled delivery of a stent

ABSTRACT

The present disclosure relates generally to the field of medical devices. In particular, the present disclosure relates to devices and methods for controlled delivery of a stent, such as a self-expanding stent, and more particularly for controlling the full deployment of a stent in incremental steps from a sheath and for controlling the reconstrainment of a stent in incremental steps within a sheath.

PRIORITY

This application claims the benefit of priority under 35 USC § 119 toU.S. Provisional Patent Application Ser. No. 62/631,228 filed Feb. 15,2018, which is incorporated by reference herein in its entirety and forall purposes.

FIELD

The present disclosure relates generally to the field of medicaldevices. In particular, the present disclosure relates to devices andmethods for controlled delivery of a stent, such as a self-expandingstent, and more particularly for controlling the full deployment of astent in incremental steps from a sheath and for controlling thereconstrainment of a stent in incremental steps within a sheath.

BACKGROUND

Stents, such as self-expanding stents, may be inserted to a targetlocation in a body lumen while constrained within a sheath. Once locatedat the target site, the stent may be deployed by retracting the sheathproximally without any restriction on the proximal movement of thesheath. Undesirable consequences of this delivery system may includepoor control over the amount of proximal movement by a user whileretracting the sheath. A user may accidentally deploy more of the stentthan intended as a result of too much withdrawing force being applied tothe sheath. For example, the entire stent may be accidentally deployedwith one proximal pulling motion of the sheath. The sheath may also beprematurely retracted proximally past a point where reconstrainment isno longer possible. These issues may result in a premature deployment ofthe stent in an undesirable location. Additionally, the existingmechanisms for deploying stents may require more than one user toactuate the mechanism, or both hands of one professional may be requiredto deploy a stent.

It may therefore be desirable to increase the amount of controlavailable to a user for delivering a stent, and/or reducing the numberof users, or hands of a single user, needed for a procedure. It is withthese considerations in mind that the improvements of the presentdisclosure may be advantageous.

SUMMARY

The present disclosure in various embodiments includes generallyapparatuses, systems and methods for controlled delivery of stents. Anexemplary device for controlled delivery of a stent may include ahandle, an inner member disposed distal to the handle and configured toextend within a lumen of the stent, and a sheath extending about theinner member and operable with the inner member to constrain the stenttherebetween. The handle may include a deployment assembly that includesa deployment member extending along a deployment axis and connected tothe constraining sheath. The assembly may be operable to translate thedeployment member in incremental steps along the deployment axis in afirst direction to at least partially deploy the stent, and may beoperable to translate the deployment member in incremental steps alongthe deployment axis in a second direction to at least partiallyconstrain the stent within the sheath. An exemplary method of using sucha device may include inserting a stent disposed on an inner member andconstrained within a sheath into a patient to a deployment location. Thesheath may be connected to an elongate deployment member and may be atleast partially retracted proximally from about the stent, and/or thestent may be at least partially reconstrained within the sheath, inincremental strokes that correspond to proximal movement and distalmovement of a deployment member along a deployment axis of the device,respectively. A single stroke may retract the sheath a distance lessthan a length of the stent and/or reconstrain the stent within thesheath a distance less than a length of the stent.

In one aspect, a device for controlled delivery of a stent, may includea handle. The device may include an elongate inner member having aproximal end and a distal end. The inner member may be disposed distalto the handle and may be configured to extend within a lumen of thestent. The device may include a constraining sheath having a proximalend and a distal end. The sheath may extend about the inner member andmay be operable with the inner member to constrain the stenttherebetween. A deployment assembly may be disposed within the handle.The deployment assembly may include an elongate deployment member havinga proximal end, a distal end, and a deployment axis extendingtherealong. The distal end of the deployment member may be connected tothe proximal end of the constraining sheath. The assembly may beoperable to translate the elongate deployment member in incrementalsteps along the deployment axis in a first direction to at leastpartially deploy the stent, and may be operable to translate thedeployment member in incremental steps along the deployment axis in asecond direction to at least partially constrain the stent. Thedeployment assembly may include a drive gear configured to engage theelongate deployment member. The deployment assembly may include a driveshaft having a drive shaft axis perpendicular to the deployment axis.The drive shaft may be axially disposed through and coupled to the drivegear. A first gear may be axially disposed about and coupled to thedrive shaft. A second gear may be axially disposed about and coupled tothe drive shaft. The second gear may be spaced apart a distance from thefirst gear along the drive shaft axis. A reversing gear may be incommunication with the second gear. A rack may be configured toalternately engage the first gear and the reversing gear. A firstone-way bearing may be coupled to the first gear and may be axiallydisposed about and coupled to the drive shaft. The first bearing may beconfigured to prevent the first gear from imparting a rotary motion tothe drive shaft that translates the deployment member in the firstdirection. A second one-way bearing may be coupled to the second gearand may be axially disposed about and coupled to the drive shaft. Thesecond bearing may be configured to prevent the second gear fromimparting a rotary motion to the drive shaft that translates thedeployment member in the second direction. The rack may have a firstlength of teeth configured to engage the first gear. The rack may have asecond length of teeth configured to engage the reversing gear. Thefirst length and the second length may be parallel to the deploymentaxis and to each other. The first length may not be coplanar in heightwith the second length. The first length may be spaced apart from thesecond length a distance that is different than the distance between thefirst gear and the second gear, such that the rack can only alternatelyengage the first length with the first gear or the second length withthe reversing gear. A cross-section of the rack in a plane normal to thedeployment axis may be substantially L-shaped. The rack may be moveableback and forth along a first axis parallel to the drive shaft axis toalternately engage one of the first gear and the reversing gear. Therack may be moveable back and forth along a second axis parallel to thedeployment axis to rotate one of the first gear and the reversing gearwhen alternately engaged therewith. The rack may include a pin extendingoutside of the handle. The pin may be engageable by a user to move therack along the first axis. The rack may include a trigger extendingoutside of the handle. The trigger may be engageable by a user to movethe rack along the second axis. Movement of the rack along the secondaxis in a proximal direction when engaging the first gear may translateto movement of the deployment member in the second direction. Movementof the rack along the second axis in a proximal direction when engagingthe reversing gear may translate to movement of the deployment member inthe first direction. The trigger may be a pistol-type trigger that maybe pulled proximally by a user to move the rack in the proximaldirection. The trigger may be a seesaw-type trigger that may rotateabout a fulcrum. The trigger may rotate from above the fulcrum and maymove the rack in the proximal direction. The trigger may rotate frombelow the fulcrum and may move the rack in a distal direction along thesecond axis. The trigger may be a thumb wheel that may be rotated by auser to move the rack in the proximal direction. The rack may bemoveable in the proximal direction along the second axis a predeterminedstroke length. The stroke length may be less than the length of thestent. The trigger may have a starting position. The deployment assemblymay further comprise one or more springs cooperatively engaged with therack to apply a biasing force onto the rack to return the trigger to thestarting position. The drive gear and the elongate deployment member mayeach comprise teeth configured to engage each other. The first directionmay be proximally along the deployment axis and the second direction maybe distally along the deployment axis. Translating the elongatedeployment member in the first direction may at least partially deploythe stent from within the sheath. Translating the elongate deploymentmember along the deployment axis in the second direction may at leastpartially constrain the stent within the sheath. The first direction maybe proximal movement of the deployment member along the deployment axisand the second direction may be distal movement of the deployment memberalong the deployment axis. The inner member and the sheath may beintegral to the handle. The inner member and sheath may be removablyattached to the handle. The inner member may extend within the handle.The sheath may include a sheath lumen and the inner member may extendcoaxially within the sheath lumen. A proximal end of the inner membermay be fixed to the handle. The inner member may be configured to holdthe stent in place relative to movement of the sheath. The deploymentmember may be one of removably connected to the sheath, fixedlyconnected to the sheath, or integral with the sheath. The deploymentmember may include a deployment member lumen coaxial with the sheathlumen. The inner member may extend coaxially through the deploymentmember.

In another aspect, a system for controlled stent delivery may include aself-expanding stent. The system may include an elongate inner memberhaving a proximal end and a distal end. The inner member may be disposeddistal to the handle and may be configured to extend within a lumen ofthe stent. The system may include a constraining sheath having aproximal end and a distal end. The sheath may extend about the innermember and may be operable with the inner member to constrain the stenttherebetween. The system may include a handle containing a deploymentassembly. The deployment assembly may include an elongate deploymentmember having a proximal end, a distal end, and a deployment axisextending therealong. The distal end of the deployment member may beconnected to a proximal end of the constraining sheath. The assembly maybe operable to translate the deployment member in incremental stepsalong the deployment axis in a first direction to at least partiallydeploy the stent, and may be operable to translate the deployment memberin incremental steps along the deployment axis in a second direction toat least partially constrain the stent. The deployment assembly mayinclude a drive gear configured to engage the elongate deploymentmember. The system may include a drive shaft, having a drive shaft axisperpendicular to the deployment axis. The drive shaft may be axiallydisposed through and coupled to the drive gear. A first gear may beaxially disposed about and coupled to the drive shaft. A second gear maybe axially disposed about and coupled to the drive shaft. The secondgear may be spaced apart from the first gear along the drive shaft axis.A reversing gear may be in communication with the second gear. A rackmay be configured to alternately engage the first gear and the reversinggear. A trigger may be configured to translate the rack proximally anddistally. The rack may be disposed on a pin that is engageable by a userfrom outside of the handle. The system may include a first one-waybearing coupled to the first gear and axially disposed about and coupledto the drive shaft. The first bearing may be configured to prevent thefirst gear from imparting a rotary motion to the drive shaft thattranslates the deployment member in the first direction. A secondone-way bearing may be coupled to the second gear and axially disposedabout and coupled to the drive shaft. The second bearing may beconfigured to prevent the second gear from imparting a rotary motion tothe drive shaft that translates the deployment member in the seconddirection. The rack may have a first length of teeth configured toengage the first gear and a second length of teeth configured to engagethe reversing gear. The first length and the second length may beparallel to the deployment axis and to each other. The first length maynot be coplanar in height with the second length. A cross-section of therack in a plane normal to the deployment axis may be substantiallyL-shaped. The rack may be moveable back and forth along a first axisparallel to the drive shaft axis to alternately engage one of the firstgear and the reversing gear. The rack may be moveable back and forthalong a second axis parallel to the deployment axis to rotate one of thefirst gear and the reversing gear when alternately engaged therewith.The trigger may have a starting position. The deployment assembly mayinclude one or more springs cooperatively engaged with the rack to applya biasing force in a distal direction onto the rack to return thetrigger to the starting position. The drive gear and the deploymentmember may each comprise teeth configured to engage each other. The rackmay include a trigger extending outside of the handle. The trigger maybe engageable by a user to move the rack along the second axis. Movementof the rack along the second axis may be in a proximal direction whenengaging the first gear, which may translate to movement of thedeployment member in the second direction. Movement of the rack alongthe second axis may be in a proximal direction when engaging thereversing gear, which may translate to movement of the deployment memberin the first direction. The rack may be moveable in the proximaldirection along the second axis a predetermined stroke length. Thestroke length may be less than the length of the stent.

In another aspect, a method of delivering a stent may include insertinga stent into a patient to a deployment location. The stent may bedisposed on an inner member and constrained within a sheath. The sheathmay have a proximal end connected to an end of an elongate deploymentmember. The deployment member may extend along a deployment axis. Thesheath may be at least partially retracted proximally from about thestent in incremental strokes, which may correspond to proximal movementof the deployment member along the deployment axis. A single stroke mayretract the sheath a distance less than a length of the stent.Retracting the sheath from about the stent may include moving a rackproximally along an axis parallel to the deployment axis. The rack maycommunicate with one or more gears to transfer the proximal movement ofthe rack, through rotation of the gears, to the proximal movement of thedeployment member. The stent may be at least partially reconstrainedwithin the sheath in incremental strokes, which may correspond to adistal movement of the deployment member along the deployment axis. Asingle stroke may reconstrain the stent within the sheath a distanceless than a length of the stent. Reconstraining the stent within thesheath may include moving a rack proximally along the axis parallel tothe deployment axis. The rack may communicate with one or more gears totransfer the proximal movement of the rack, through rotation of thegears, to the distal movement of the deployment member. Retracting thesheath and reconstraining the stent within the sheath by the sameproximal movement of the rack may include switching the rack fromengaging one gear of the one or more gears to engaging another gear ofthe one or more gears. Retracting the sheath and reconstraining thestent within the sheath may be performed by movement of a trigger thatis in communication with the rack. The trigger may be a pistol-typetrigger, thumb wheel, or seesaw-type trigger. The deployment member maybe removably connected to the sheath, fixedly connected to the sheath orintegral with the sheath.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the present disclosure are described by wayof example with reference to the accompanying figures, which areschematic and not intended to be drawn to scale. In the figures, eachidentical or nearly identical component illustrated is typicallyrepresented by a single numeral. For purposes of clarity, not everycomponent is labeled in every figure, nor is every component of eachembodiment shown where illustration is not necessary to allow those ofordinary skill in the art to understand the disclosure. In the figures:

FIG. 1 illustrates a device delivering a self-expanding stent, inaccordance with an embodiment of the present disclosure.

FIG. 2 illustrates a perspective view of a deployment assembly, inaccordance with an embodiment of the present disclosure.

FIG. 3A illustrates a device having a handle and a deployment assemblywith a pistol-type trigger, in accordance with an embodiment of thepresent disclosure.

FIG. 3B illustrates a section of the device of FIG. 3A.

FIG. 4 illustrates a device having a handle and a deployment assemblywith a seesaw-type trigger, in accordance with an embodiment of thepresent disclosure.

FIG. 5 illustrates a device configured to accommodate other existingstent deployment devices, in accordance with an embodiment of thepresent disclosure.

FIG. 6 illustrates a further device with an elongate deployment member,in accordance with an embodiment of the present disclosure.

FIG. 7A illustrates a left view of a device including a motor and adeployment member, in accordance with an embodiment of the presentdisclosure.

FIG. 7B illustrates the device of FIG. 7A with the deployment member ina position that is more proximal than the position of the deploymentmember in FIG. 7A.

FIG. 7C illustrates the device of FIGS. 7A and 7B with the deploymentmember in a position that is more distal than the position of thedeployment member in FIGS. 7A and 7B.

DETAILED DESCRIPTION

The present disclosure is not limited to the particular embodimentsdescribed. The terminology used herein is for the purpose of describingparticular embodiments only, and is not intended to be limiting. Unlessotherwise defined, all technical terms used herein have the same meaningas commonly understood by one of ordinary skill in the art to which thedisclosure belongs.

Although embodiments of the present disclosure are described withreference to a “stent”, it should be appreciated that a variety of otherdevices may be configured for controlled delivery in accordance with thepresent disclosure. Examples of such devices include devices for venacava biopsies, suturing devices, snares forceps, and the like. Inpractice, any device or procedure that may benefit from controlleddelivery and release could be used with embodiments of this disclosure.

Although embodiments of the present disclosure are described withreference to a “body lumen”, it should be appreciated that a “bodylumen” may refer to a variety of organs, systems, tracts, vessels,and/or cavities, such as the gastrointestinal system, vascular system,urogenital system, lymphatic system, neurological system, and the like.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” or “includes” and/or “including” when used herein,specify the presence of stated features, regions, steps elements and/orcomponents, but do not preclude the presence or addition of one or moreother features, regions, integers, steps, operations, elements,components and/or groups thereof.

As used herein, the conjunction “and” includes each of the structures,components, features, or the like, which are so conjoined, unless thecontext clearly indicates otherwise, and the conjunction “or” includesone or the others of the structures, components, features, or the like,which are so conjoined, singly and in any combination and number, unlessthe context clearly indicates otherwise.

As used herein, the term “distal” refers to the end farthest away fromthe medical professional when introducing a device into a patient, whilethe term “proximal” refers to the end closest to the medicalprofessional when introducing a device into a patient.

Embodiments of the present disclosure include devices, systems andmethod used to provide controlled delivery of a stent. A stent may bewithin a constraining sheath that is about the stent. A portion of thestent may be in a constrained configuration while within the sheath anda portion of the stent may be in an unconstrained configuration whileoutside of the sheath. The stent may be self-expanding and include alumen extending therethrough that is of a constant or varying diameter.The stent may be configured in any manner of shape depending on theapplication and may include a retention member (e.g., flare or flange)on the distal and/or proximal end of the stent. The stent may be wovenor knitted out of multiple filaments or a single filament and mayinclude a single weave or knitted pattern throughout the stent, or thepattern may vary. A filament may have a variety of cross-sectionalshapes, e.g., round, oval, rectangular, etc. A filament may comprise ashape memory material such as nitinol, platinol, a shape memory polymer,or the like. The stent may be comprised of a biocompatible metallic orpolymeric material. The stent may be coated or covered with a polymericmaterial along the entire length and circumference of the stent or alongportions of the length or circumference of the stent, or both.Non-polymeric coating material may alternatively be used. Suitablecoating materials include, for instance, polymeric materials,drug-infused polymeric materials (including therapeutic agents, e.g.,sirrolumus, everolimus, paclitaxel, anti-inflammatories, and the like),such as polytetrafluoroethylene or silicone rubbers, polyurethanes,polyvinylidene fluoride, polyethylene terephthalate, polymethylmethacrylate, poly lactic-co-glycolic acid, or ChronoFlex®, which areknown to be biocompatible. A stent may be configured in a variety ofdimensions depending on, for example, the medical use and/or the anatomyin which it is being used. For example, a stent for endoscopic use mayhave a diameter in the range of about 5 mm to about 30 mm, and may havea length of about 5 mm to about 200 mm.

Embodiments of the present disclosure may include a constraining sheaththat may be moveable over a stent to deploy the stent from the sheathand/or reconstrain the stent within the sheath. The sheath may containthe stent within the sheath in a constrained configuration duringinsertion into a body lumen. The constrained configuration may include areduced profile of the stent. Once the sheath and constrained stent arein a desired location, the sheath may be moved proximally over the stentto initiate deployment of the stent from a constrained configuration toan unconstrained configuration (for example, in the case of aself-expanding stent comprised of shape memory material, from anunexpanded stressed configuration to an expanded unstressedconfiguration). The sheath may be moved distally over the stent toreconstrain at least a portion of the stent within the sheath in theconstrained (e.g., unexpanded) configuration. A constraining sheath mayhave a proximal end and a distal end, and may extend about an elongateinner member. The sheath may have a lumen along the length of the sheathwith the inner member extendable coaxially within the sheath lumen. Thesheath may be operable with the inner member to constrain the stenttherebetween. A sheath may be integral with a handle or the sheath maybe removably attached to the handle. A sheath may be connected with adeployment member or the sheath may be integral with the deploymentmember. A deployment member may be removably connected or fixedlyconnected with a sheath. A lumen of the sheath may be co-axial with alumen of the deployment member.

Embodiments of the present disclosure may include an inner member. Theinner member may be disposed distal to a handle and configured to extendwithin a lumen of a stent. The inner member may be configured to holdthe stent in place with respect to relative movement of the sheathproximally and distally about the stent and inner member. The innermember may extend along the length of the sheath and may be flexible toassist in guiding the sheath and stent while inserting the stent to atarget site in a body lumen. The inner member may be fixed in positionrelative to a handle of a device (e.g., a proximal end of the innermember by fixed within the handle housing), such that a proximal ordistal movement of the sheath with respect to the inner member (and thehandle, when the inner member is fixed thereto) will translate intoproximal or distal movement of the sheath along the stent. The innermember may include at least one barb, fin, step-down, band, holder,hook, tine, or the like to retain the stent until the stent is fullydeployed. The inner member may extend through an elongate deploymentmember, extend adjacently along the elongate deployment member, extendadjacently along the handle, extend within the handle, and/or extendaway from the handle. The deployment member may include a deploymentmember lumen coaxial with the sheath lumen, and the inner member mayextend coaxially through the deployment member. An inner member mayinclude a lumen extending along the length of the inner member. Othermedical instruments or devices may be disposed and/or extended throughthe lumen of the inner member to access a deployment site, such as aguidewire, or the lumen may be used to inject materials to the site,such contrast for imaging, therapeutic agents, etc. An inner member andconstraining sheath, with or without a stent loaded therebetween, may beof a conventional delivery system with handle(s) that are capable ofbeing retrofit with a device, and used in a procedure, in accordancewith embodiments of the present disclosure. Alternatively, embodimentsof the disclosure may be an inner member and sheath, with or without astent loaded therebetween, that is configured as a standalone disposablethat may be removably attached to a handle and deployment member of adevice, which may be reusable. As a further alternative, embodiments ofthe disclosure may be an inner member and a sheath, with or without astent loaded therebetween, that is configured integral with or fixedlyconnected to a handle and deployment member, as a complete device andsystem, which may be disposable as a whole after use.

With reference to FIG. 1, an embodiment of a device and system forcontrolled delivery of a stent according to the present disclosure isillustrated. The device may be configured for use with stent, or asystem may include a device and a stent 104, pre-loaded or loadable onthe device. The stent 104 is shown partially deployed with a distalportion of the stent in an unconstrained configuration and a proximalportion of the stent in a constrained configuration. The portion of thestent 104 in the constrained configuration is within a constrainingsheath 102. An elongate inner member 106 extends within a lumen of thestent 104 and may extend some distance beyond the distal end of thestent. The inner member 106 extends along the length of the sheath 102.A deployment assembly 108 is disposed within a handle 100 and within adeployment assembly portion 101 of the handle 100 that is illustrated inphantom lines. Similar deployment assembly portions 101 of a handle 100may be included with other embodiments described herein and otherwisewithin the scope of the disclosure. A proximal end of the inner membermay be fixed in position relative to the handle and terminate in a luerfitting, as shown, at the proximal end of the handle. A lumen may extendthrough the inner member and communicate co-axially with an aperture inthe luer fitting for purposes of receiving instruments and/or materialsor fluids through the lumen to a deployment location.

With reference to FIG. 2, an embodiment of a deployment assembly 208, aspart of a device or system of the present disclosure, such as theassembly 108 within the handle 100 of the device in FIG. 1, isillustrated. An elongate deployment member 210 of the assembly has aproximal end 210 p, a distal end 210 d, an inner lumen 2101 extendingtherethrough, and a deployment axis extending therealong from theproximal end 210 p and the distal end 210 d. The distal end 210 d may beconnected to a proximal end of a constraining sheath. The assembly 208is operable to translate the elongate deployment member 210 inincremental steps along the deployment axis in a first direction (e.g.,proximally) to at least partially unconstrain and/or deploy a stent thatmay be disposed on an inner member and constrained between the innermember and the sheath. A drive gear 212 is configured to engage theelongate deployment member 210. The drive gear 212 and the elongatedeployment member 210 each have teeth configured to engage each other,such that rotation of the drive gear imparts translational movement tothe deployment member along the deployment axis. Although teeth areshown, other ways may be envisioned to engage the drive gear anddeployment member to achieve a similar arrangement and movement. A driveshaft 228, having a drive shaft axis perpendicular to the deploymentaxis, is axially disposed through and coupled to the drive gear 212. Afirst gear 216 is axially disposed about and coupled to drive shaft 228.A second gear 214 is axially disposed about and coupled to the driveshaft 228, and is spaced apart a distance from the first gear 216 alongthe drive shaft 228. A reversing gear 218 is disposed about pin 219. Thereversing gear 218 has teeth that are engaged with teeth on the secondgear 214, such that rotation of the reversing gear imparts a reverserotation of the second gear (see arrows in FIG. 2), which impartstranslational movement to the deployment member along the deploymentaxis. A first one-way bearing 232 is coupled to the first gear 216. Thefirst one-way bearing 232 is axially disposed about and coupled to thedrive shaft 228 and is configured to prevent the first gear 216 fromimparting a rotary motion to the drive shaft 228 that translates thedeployment member 210 in a first direction (e.g., proximally). A secondone-way bearing 230 is coupled to the second gear 214. The secondone-way bearing 230 is axially disposed about and coupled to the driveshaft 228 and is configured to prevent the second gear 214 fromimparting a rotary motion to the drive shaft 228 that translates thedeployment member 210 in a second direction (e.g., distally). A rack 220is configured to alternately engage the first gear 216 and the reversinggear 218. The rack 220 has a first length of teeth 224 configured toengage the first gear 216 and a second length of teeth 222 configured toengage the reversing gear 218. The first length 224 and the secondlength 222 are parallel to the deployment axis and to each other. Thefirst length of teeth 224 is not coplanar in height with the secondlength of teeth 222. A cross-section of the rack 220 in a plane normalto the deployment axis is substantially L-shaped. This allows the firstlength of teeth 224 to engage the first gear 216 closer to the driveshaft axis and the second length of teeth 222 to engage the reversinggear 218, which is situated farther from the drive shaft axis. The rack220 is configured to alternately engage the first gear 216 and thereversing gear 218, but not at the same instant. In FIG. 2, the firstlength of teeth 224 is shown engaging the first gear 216, while thesecond length of teeth 222 is not engaging the reversing gear 218. Therack 220 alternately engages one of the first gear 216 and the reversinggear 218 because the first length of teeth 224 is spaced apart adistance from the second length of teeth 222 that is different than adistance between the first gear 216 and the second gear 214. Theassembly 208 may be within a housing, with the shaft 228 and pin 219having at least one end extending into the housing and being able torotate freely within the housing. In various embodiments, the pin may bea T-shaped pin that is connected to a side of the housing only at oneend of the pin. The rack 220 is moveable back and forth within thehousing of the handle along a first axis parallel to the drive shaftaxis to alternately engage one of the first gear 216 and the reversinggear 218. The rack 220 includes a pin 226 extending outside of thehandle 200. The pin 226 is engageable by a user to move the rack alongthe first axis. The rack 220 is moveable back and forth along a secondaxis parallel to the deployment axis to rotate one of the first gear 216and the reversing gear 218 when alternately engaged therewith. With thisarrangement of a deployment assembly, the movement of the rack 220 maybe controlled and may have a predetermined stroke length so as to movethe deployment member 210 and an attached constraining sheath a distanceless than the length of the stent. The first length of teeth 224 of therack 220 may engage the first gear 216. Proximal movement of the rack220 and the first length of teeth 224 while engaging the first gear 216rotates the first gear 216 and the drive shaft 228 in the direction ofthe arrow near the first gear such that the drive gear 212 translatesthe deployment member 210 distally. The sheath connected to thedeployment member is moved distally a distance that reconstrains aportion of a stent that has been partially deployed. A return stroke ofthe first length of teeth 224 and the rack 220 in a distal directionwhile engaged with the first gear 216 rotates the first gear 216 in adirection opposite of the arrow near the first gear 216. This opposingrotation of the first gear 216 is not translated to the drive shaft 228because of the first one-way bearing 232. This movement may be repeated,as desired, to further reconstrain the stent within the sheath. Thesecond length of teeth 222 of the rack 220 may engage the reversing gear218 that is engaged with the second gear 214. Proximal movement of therack 220 and the second length of teeth 222 while engaging the reversinggear 214 rotates the reversing gear 218 in the direction of the arrownearest the reversing gear 218. The reversing gear 218 rotates thesecond gear 214 and the drive shaft 228 in the direction of the arrownearest the second gear 214 such that the drive gear 212 translates thedeployment member 210 proximally. The sheath connects to the deploymentmember, is retracted or moved proximally a distance that deploys orunconstrains a portion of the stent from within the sheath. A returnstroke of the second length of teeth 222 and the rack 220 in a distaldirection while engaged with the reversing gear 218 rotates the secondgear 214 in a direction opposite of the arrow nearest the second gear214. This opposing rotation of the second gear 214 is not translated tothe drive shaft 228 because of the second one-way bearing 230. Thismovement may be repeated, as desired, to further deploy the stent.

With reference to FIGS. 3A and 3B, an embodiment of a device forcontrolled delivery of a stent according to the present disclosure isillustrated, which includes a handle 300 containing a deploymentassembly 308 disposed within the handle 300. The deployment assembly308, which may be configured similarly to the gear and rack arrangementdescribed with reference to FIG. 2, includes an elongate deploymentmember 310 with a proximal end, a distal end, an inner lumentherethrough, and a deployment axis extending therealong. The distal endof the elongate deployment member 310 is connected to a proximal end ofa constraining sheath 302 via a connection member 340. The connectionmember 340 is shown as ergonomically shaped for a user to grab hold ofit with their hand, should the user desire rapid deployment orreconstrainment. The connection member 340 may be used to rapidlyunconstrain or reconstrain the stent by manually moving the connectionmember 340 proximally or distally. The user may rapidly move theconnection member 340 while the rack 320 is engaged with a reversinggear 318 or a first gear 316 so long as the drive gear 312 is rotated bythe deployment member 310 such that the drive shaft does not transferrotation to the first gear 316 or a second gear 314 via the one-waybearings. The assembly 308 is operable to translate the elongatedeployment member 310 in incremental steps along the deployment axis ina first direction (e.g., proximally) to at least partially deploys astent constrained between an inner member 306 and the sheath 302. Theassembly 308 is also operable to translate the deployment member 310along the deployment axis in a second direction (e.g., distally) to atleast partially constrain the stent. The assembly 308 also includes adrive gear 312 configured to engage the elongate deployment member 310.A drive shaft, having a drive shaft axis perpendicular to the deploymentaxis, is axially disposed through and coupled to the drive gear 312. Afirst gear 316 is axially disposed about the drive shaft. A second gear314 is axially disposed about the drive shaft and spaced apart adistance from the first gear 316 along the length of the drive shaft. Afirst one-way bearing is coupled to the first gear 316. The firstone-way bearing is axially disposed about and coupled to the drive shaftand is configured to prevent the first gear 316 from imparting a rotarymotion to the drive shaft that translates the deployment member 310 inthe first direction. A second one-way bearing is coupled to the secondgear 314. The second one-way bearing is coupled to the drive shaft andis configured to prevent the second gear 314 from imparting a rotarymotion to the drive shaft that translates the deployment member 310 inthe second direction. A reversing gear 318 is engaged with the secondgear 314. The elongate inner member 306 is configured to be at leastpartially disposed within a lumen of the stent and extend along thesheath 302. A rack 320 includes a pin 326 that extends outside of thehandle 300 and is engageable by a user to move the rack along a firstaxis parallel to the drive shaft axis to alternately engage one of thefirst gear 316 and the reversing gear 318. The rack 320 includes atrigger 330 extending outside of the handle 300, which is shown as apistol-type trigger. The trigger 330 is engageable by the user to movethe rack 320 along a second axis parallel to the deployment axis torotate one of the first gear 316 and the reversing gear 318 whenalternately engaged therewith. The pistol-type trigger 330 may be pulledproximally by a user to move the rack 320 in the proximal direction. Thepin 326 connected to the rack 320 is disposed through the trigger 330,such that movement of the pin 326 and the rack 320 along the first axisthrough the trigger 330 allows the user to shift the rack 320 back andforth along the first axis to alternately engage the rack 320 with thefirst gear 316 and the reversing gear 318. Switching the rack 320between the first gear 316 and the reversing gear 318 changes thedirection that the deployment member 310 will move with a stroke of thetrigger 330. For example, movement of the rack 320 along the second axisin a proximal direction when engaging the first gear 316 translates tomovement of the deployment member 310 in the second direction, which maybe distally to reconstrain the sheath 302 about the stent. Movement ofthe rack 320 along the second axis in a proximal direction when engagingthe reversing gear translates to movement of the deployment member inthe first direction, which may be proximally to deploy the stent. Therack 320 is moveable along the second axis parallel to the deploymentaxis to translate the rack 320 a predetermined stroke length. The strokelength is the length that the trigger 330 covers when moved proximallytoward the handle 300 (e.g., a full trigger squeeze). The trigger 330has a starting position. The deployment assembly 308 has one or moresprings 328 (two illustrated in FIG. 3) cooperatively engaged with therack 320 to apply a biasing force onto the rack 320 to return thetrigger 330 to the starting position. Each spring 328 is disposed abouta rod 303, the rod spanning from a grip of the handle 300 thatterminates at an end feature 301 within the handle 300. The trigger 330includes a trigger housing in which the rack 320 is disposed. The rodsextend through the trigger housing, such that the housing with the rack320 is slidably disposed along the rods to translate movement of therack 320 along the second axis. The trigger housing is also sized toaccommodate movement of the rack 320 along the first axis, e.g., when auser engages pin 326 to switch the direction of the deployment member310 between retracting the sheath 302 to deploy the stent and moving thesheath to reconstrain the stent. In FIG. 3, the trigger 330 is shown inthe starting position with the rack 320 engaging the reversing gear 318.The first one-way bearing and second one-way bearing prevent the firstgear 316 and second gear 314 from transferring rotational forces to thedrive shaft when the rack moves distally to the return to the startingposition, such that as the spring 328 returns the trigger 330 to thestarting position, no movement is transferred to the deployment member310 regardless of which gear (the first gear or the reversing gear) isengaged. The stent may be held in place relative to the sheath 302 viathe inner member 306. The constraining sheath 302 is operable with theinner member 306 to constrain the stent therebetween. The inner member306 is shown extending through the elongate deployment member 310, butin other embodiments an inner member may extend alongside. The innermember 306 may extend up to and terminate in a luer fitting 332. Similarluer fittings may be used with other embodiments described herein andotherwise within the scope of the disclosure.

A scale 336 is disposed along the handle 300 such that a user may viewand measure a distance that the elongate deployment member 310 hastraveled, which may be calibrated to corresponds to an equivalentmovement of the sheath 302 with respect to the stent. The scale 336 mayinclude an indicator pointing to markings and/or the scale 336 may betranslucent or slotted such that the deployment member 310 is visiblealong the scale 336 for the user to view and/or measure. A certain partof the scale 336 and/or the elongate deployment member 310 may be markedto indicate when the sheath 302 may be reaching a point where the sheath302 can no longer reconstrain the stent. Similar scales, markings, andmaterials may be used with other embodiments described herein andotherwise within the scope of the disclosure. FIGS. 3A and 3B illustratea similar arrangement for a deployment assembly of FIGS. 1 and 2, butare being used to highlight features such as the trigger 330, springs328, scale 336, luer fitting 332, and to describe the deploymentassembly in further detail.

In various embodiments within the scope of the present disclosure, astroke length may be a distance that a trigger moves a rack with a fullactivation of the trigger. A stroke length may be less than a length ofthe stent. A stroke of a trigger may translate the elongate deploymentmember in a first direction (e.g., proximally along a deployment axis)in incremental steps. This movement with sheath attached to thedeployment member retracts the sheath from about the stent to at leastpartially deploy the stent. A stroke of a trigger with the rack engagedwith a reversing gear may move the deployment member proximally, inincremental steps, unconstraining or retracting the sheath from aboutthe stent to at least partially deploy the stent. A stroke of a triggermay translate the elongate deployment member in a second direction(e.g., distally along the deployment axis) in incremental steps. Thismovement with the sheath attached to the deployment member at leastpartially constrains the stent within the sheath. A stroke of thetrigger with the rack engaged with the first gear may move thedeployment member distally, in incremental steps, at least partiallyconstraining the stent within the sheath (e.g., reconstraining the stentwithin the sheath by moving the sheath back over a portion of the stentalready deployed). The distance that the sheath moves relative to thestent, in a constraining or unconstraining fashion, may relate to thestroke length by a ratio that may be any suitable ratio depending on thegear configuration that is chosen, for example, 1:1, 1:2, 1:3, 1:4, 1:5,1:6, 1:7, 1:8, 1:4, 1:9, 1:10, etc. It should be appreciated that a fullactivation of the trigger cannot deploy the stent from a fullyconstrained configuration within the constraining sheath to a deployedand fully unconstrained configuration so long as a stroke length of thetrigger translates to a movement of the sheath that is less than thelength of the stent. A deployment assembly may translate the elongatedeployment member in incremental steps with each step being a stroke.Alternatively, each stroke may be made up of more than one incrementalstep for translating the deployment member. In various embodiments, astroke length may be adjusted by changing the distance that the triggermoves, the length of the rack, the length of the rack that engages agear, the travel distance of the rack, the ratio of gears translatingrotation to the drive shaft, the size of the gears, the size of the gearteeth, and the like. Such stroke variations may be achieved by, forexample, adjusting a stop block by manipulating an adjustable screw thatimpedes the stroke length by limiting the distance that the rack and ortrigger may be moved. A cushioning zone may be configured in a device ata point where a stent is close to being deployed from the sheath and thesheath may not be able to reconstrain the stent. The cushioning zone maybe a predetermined distance that the deployment member and the sheathmay be retracted before reaching the point where the sheath can nolonger be reconstrained about the stent. A portion of the length ofdistance traveled by the deployment member just before this point may bedesignated as the cushioning zone. Once the deployment member has beentraveled a length of distance that enters the cushioning zone, a stopblock or pin may impede the trigger and/or rack from completing thecurrent stroke length. If desired at that point to fully deploy, thestop block or pin may be released with a release of the trigger, and oneadditional final pull of the trigger may then move the deployment memberpast the cushioning zone. When the retraction of a sheath reaches thiscushioning zone, the user may be alerted and/or a new stroke may berequired to get past the cushioning zone for deployment. Upon reachingthe cushioning zone, the user may still reconstrain the stent and/orreposition the stent to a desired location. Additionally oralternatively, a setting may be configured on a device that engages therack with a third gear on the drive shaft, such that a user may deploythe stent in one motion, without a stroke length restricted by the rangeof movement of the rack, should controlled deployment be unnecessaryand/or too time consuming for the procedure. This may also beaccomplished with a third length of teeth on the rack or the third gearhaving a higher ratio of stroke length to gear rotation than that of thefirst gear, second gear, reversing gear, first length of teeth, andsecond length of teeth. A rack may also have a setting that disengagesthe gears, such as a clip that moves the rack down off of the gears toallow manual manipulation of the deployment member for deployment and/orreconstrainment of the stent without use of a trigger and its confinedstroke length.

With reference to FIG. 4, an embodiment of a device for controlleddelivery of a stent according to the present disclosure is illustrated,which includes a handle 400 containing a deployment assembly 408. Adrive gear 412 is configured to engage the elongate deployment member410 and has a deployment axis through the member 410. A drive shaft,having a drive shaft axis perpendicular to the deployment axis, isaxially disposed through and coupled to the drive gear 412. A rack 420is configured to engage the drive gear 412. The rack 420 is connected toa trigger 430 outside of the handle 400 to move the rack. The trigger430 is a seesaw-type trigger that rotates about a fulcrum 434. The rack420 is moveable along an axis parallel to the deployment axis. The topof the trigger 430 is pivotally connected to the rack 420 via a pin andslotted member 436. The slotted member 436 translates the rotation ofthe trigger 430 about the fulcrum 434 to the rack 420. In this way, therotational arc segment that the trigger 430 travels is translated intolinear movement of the rack 420 along the second axis parallel with thedeployment axis. A user may rotate and/or pull the trigger 430 about thefulcrum 434 in a clockwise direction (e.g., by pulling proximally on thetop portion of the trigger 430) to move the rack 420 in a proximaldirection. A user may rotate the trigger 430 about the fulcrum 434 in acounter-clockwise direction (e.g., by pulling proximally on the bottomportion of the trigger 430) to move the rack 420 in a distal direction.The proximal and distal movement of the rack 420 is transferred to thedrive gear 412 and to the elongate deployment member 410. With theelongate deployment member 410 attached to a restraining sheath, theuser may constrain and unconstrain portions of the stent by rotatingand/or pulling the trigger 430 about the fulcrum 434 in clockwise andcounter-clockwise directions. The user, for example, may unconstrain thestent from the sheath by pulling on the bottom portion of the trigger430 (the portion below the fulcrum 434) and may reconstrain the sheathover the stent by pulling on the top portion of the trigger 430,returning the trigger 430 to the starting position. FIG. 4 illustratesthe rack 420 being at the proximal-most point of the stroke of thetrigger 430 in the starting position. Distal motion of the rack 420 canfully deploy the stent from the sheath with a full pull of the bottomportion of the trigger 430. If desired, a user can reconstrain thesheath about the stent with a full pull of the top portion of thetrigger 430 moving the deployment member 410 distally and the rack 420to its proximal-most starting point. The stent may be held in placerelative to the sheath via an inner member that is at least partiallydisposed within the stent and extending along the sheath. The innermember may extend through or alongside the elongate deployment member410. The inner member may extend up to and terminate at a luer fitting432. Some medical devices may be shorter in length than some of thestents described herein (e.g., such as stent 104), and may require lessthan a stroke length for unconstrainment and reconstrainment.Embodiments like the one illustrated in FIG. 4 may have a shorter strokelength in the proximal or distal direction than, for example, theembodiments shown in FIGS. 1 through 3B. Additionally, there may be noneed for a user to take the additional step of moving the rack 420 alonga first axis parallel to a drive shaft axis to engage a gear other thanthe drive gear 412 because the deployment member 410 may be movedproximally or distally with the rotation of the drive gear 412unconstraining or constraining, respectively, the entirety of the stentin one stroke.

In various embodiments described here or otherwise within the scope ofthe present disclosure, the trigger may be a variety of mechanisms formoving a rack. For example, the trigger may be a pistol-type trigger, aseesaw-type trigger, a thumb wheel, hand pump, jack level, or the like.FIG. 4 shows a trigger arrangement that may be implemented similarly ina thumb wheel. For example, a trigger that is a thumb wheel may berotated to move the rack along the second axis in a first direction thattranslates to movement of the deployment member in a second opposingdirection. Rotation of the thumb wheel in an opposite direction movesthe rack along the second axis in the second direction that translatesto movement of the deployment member in the first opposing direction. Anembodiment of a thumb wheel may alternatively be configured similar tothe pistol-type trigger deployment assembly of FIGS. 1-3B, andoptionally have springs similar to that of FIG. 3A, or a rotary springwithin the wheel, that operates only to move the rack proximally by apredetermined stroke length. A rotation of a trigger that is athumbwheel may be a rotation of a number of degrees equal to a strokelength of the trigger and/or rack. The number of degrees of rotation ofthe thumb wheel may translate to a portion of the stroke length and mayinclude an auditory signal (e.g., a “click”) that alerts the user to acertain length of distance that the sheath has been moved relative tofull deployment or reconstrainment of the sheath. For example, each“click” could be about 30° corresponding to about 5 mm of sheathmovement. In other embodiment the amount of degree of rotation of thewheel may be matched to the movement of the sheath, as desired for theparticular application and configuration of stent. The deployment membermay be translated in incremental steps that may be a portion of a strokelength or an entire stroke length. A trigger may be motorized and may becontrolled by a computer with pre-programmed instructions for the stentto a location and/or deploying the stent. Embodiments having a triggerand a handle may allow a user to insert and deploy a stent using onlyone hand. This may allow the user to maintain tension on the stent,reduce the need for additional user s, and/or allow the user to operateanother device such as, for example, a scope or the like. A trigger mayhave a safety lock that prevents the trigger from moving and possiblyinadvertent stent deployment.

With reference to FIG. 5, an embodiment of a device for controlleddelivery of a stent according to the present disclosure is illustrated,which includes a handle 500 containing a deployment assembly 508 similarto the arrangement described above with respect to FIGS. 2, 3A, and 3B.A distal holder 540 is disposed onto an elongate deployment member 510.A proximal holder 538 is disposed onto the handle 500. The distal holder540 moves proximally and distally with the proximal and distal movementof the elongate deployment member 510. The distal holder 540 has animpression 544 configured to accept a distal handle 546 that is attachedto a constraining sheath 502. The proximal holder 538 has an impression548 configured to accept a proximal handle 550 that is attached to aninner member 506 disposed through the distal handle 546 and theconstraining sheath 502. The impressions 544 and 548 may have shouldersthat create a reversible snap-fit arrangement with the handles 546 and550. Such a device can be used with conventional delivery devices toretrofit a device for controlled delivery. With the distal handle 546within the distal holder 540 and the proximal handle 550 within theproximal holder 538, the distal holder 540 may be moved with respect tothe proximal holder 538 to move the sheath 502 with respect to the stentand the inner member 506. During operation, the proximal handle 550 andinner member 506 remain stationary with respect to the distal handle 546and the sheath 502. The inner member 506 may hold the stent stationaryduring movement of the sheath 502 for unconstraining and reconstrainingof the stent via movement of the elongate deployment member 510, thedistal holder 540, and the distal handle 546.

With reference to FIG. 6, an embodiment of a device for controlleddelivery of a stent according to the present disclosure is illustrated,which includes a handle 600 containing a deployment assembly 608. Anelongate deployment member 610 is at least semi-flexible such that itretracts in a proximal direction towards the proximal end of the handle600, and then towards a bottom portion of the handle 600 towards a luerfitting 632. A proximal end of a sheath 603 is connected to the distalend of the deployment member 610. An elongate inner member 606 is atleast partially disposed within a lumen of the stent and extends alongthe sheath 602, and through the deployment member 610 to the luerfitting 632.

With reference to FIGS. 7A-7C, an embodiment of a device for controlleddelivery of a stent according to the present disclosure is illustrated,which includes a motor 713 connected to a drive gear 712 to move adeployment member 710 in a proximal or distal direction. The directionand activation of the motor 713 may be driven by a user-operatedring-shaped trigger 730 in which a finger may be inserted and pushedand/or pulled to move the trigger distally and proximally, respectively.A medical device, such as a stent, may be unconstrained by the userpulling on the trigger 730 towards the handle 700 and about the triggerpin 734 (e.g., FIG. 7B), which activates a first switch 715 configuredto drive the motor 713 in a first direction. The medical device may bereconstrained by the user pushing on the trigger 730 away from thehandle 700 (e.g., FIG. 7C), which activates a second switch 717configured to drive the motor 713 in a second direction. The firstdirection may be to drive the deployment member proximally, and thesecond direction may be to drive the deployment member distally. Themotor drives the drive gear 712, which moves the deployment member 710.The motor may be battery operated, with the batteries stored within thehandle 700 or in a compartment external to the handle 700 for easyaccess. The motor 713 may alternatively be powered by an AC source incombination with an AC/DC transformer external to the handle 700 andconnected to a power cord.

In variations of the embodiments described here or otherwise within thescope of the present disclosure, a method of delivering a stent mayinclude inserting a stent into a patient to a deployment location. Thestent may be disposed on an inner member and constrained within asheath. The sheath may have a proximal end connected to an end of anelongate deployment member. The deployment member may extend along adeployment axis. The sheath may be at least partially retractedproximally from about the stent in incremental strokes, whichcorresponds to proximal movement of the deployment member along thedeployment axis. A single stroke may retract the sheath a distance lessthan a length of the stent. Retracting the sheath from about the stentmay include moving a rack proximally along an axis parallel to thedeployment axis. The rack may communicate with one or more gears totransfer the proximal movement of the rack, through rotation of thegears, to the proximal movement of the deployment member. The stent maybe at least partially reconstrained within the sheath in incrementalstrokes, which may correspond to a distal movement of the deploymentmember along the deployment axis. A single stroke may reconstrain thestent within the sheath a distance less than a length of the stent.Reconstraining the stent within the sheath may include moving a rackproximally along the axis parallel to the deployment axis. The rack maycommunicate with one or more gears to transfer the proximal movement ofthe rack through rotation of the gears, to the distal movement of thedeployment member. Retracting the sheath and reconstraining the stentwithin the sheath may be by the same proximal movement of the rack andmay be by switching the rack from engaging one gear of the one or moregears to engaging another gear of the one or more gears. The sheath maybe retracted and may reconstrain the stent within the sheath by movementof a trigger that is in communication with the rack. The trigger may bea pistol-type trigger, thumb wheel, or seesaw-type trigger. Thedeployment member may be one of removably connected to the sheath,fixedly connected to the sheath, or integral with the sheath. Thedeployment member may be removably engageable with the sheath.

All of the devices and/or methods disclosed and claimed herein can bemade and executed without undue experimentation in light of the presentdisclosure. While the devices and methods of this disclosure have beendescribed in terms of certain embodiments, it may be apparent to thoseof skill in the art that variations can be applied to the devices and/ormethods and in the steps or in the sequence of steps of the methodsdescribed herein without departing from the concept, spirit and scope ofthe disclosure. All such similar substitutes and modifications apparentto those skilled in the art are deemed to be within the presentdisclosure.

What is claimed is:
 1. A device for controlled delivery of a stent,comprising: a handle; an elongate inner member having a proximal end anda distal end, the inner member disposed distal to the handle andconfigured to extend within a lumen of the stent: a constraining sheathhaving a proximal end and a distal end, the sheath extending about theinner member and operable with the inner member to constrain the stenttherebetween; and a deployment assembly disposed within the handle,comprising: an elongate deployment member having a proximal end, adistal end, and a deployment axis extending therealong, the distal endof the deployment member connected to the proximal end of theconstraining sheath, wherein the assembly is operable to translate theelongate deployment member in incremental steps along the deploymentaxis in a first direction to at least partially deploy the stent, and isoperable to translate the deployment member in incremental steps alongthe deployment axis in a second direction to at least partiallyconstrain the stent.
 2. The device of claim 1, wherein the deploymentassembly further comprises: a drive gear configured to engage theelongate deployment member; a drive shaft having a drive shaft axisperpendicular to the deployment axis, the drive shaft axially disposedthrough and coupled to the drive gear; a first gear axially disposedabout and coupled to the drive shaft; a second gear axially disposedabout and coupled to the drive shaft, the second gear spaced apart fromthe first gear along the drive shaft axis; a reversing gear incommunication with the second gear; and a rack configured to alternatelyengage the first gear and the reversing gear
 3. The device of claim 2,further comprising: a first one-way bearing coupled to the first gearand axially disposed about and coupled to the drive shaft, the firstbearing configured to prevent the first gear from imparting a rotarymotion to the drive shaft that translates the deployment member in thefirst direction; and a second one-way bearing coupled to the second gearand axially disposed about and coupled to the drive shaft, the secondbearing configured to prevent the second gear from imparting a rotarymotion to the drive shaft that translates the deployment member in thesecond direction.
 4. The device of claim 2, wherein the rack has a firstlength of teeth configured to engage the first gear and a second lengthof teeth configured to engage the reversing gear, wherein the firstlength and the second length are parallel to the deployment axis and toeach other.
 5. The device of claim 4, wherein the first length is spacedapart from the second length a distance that is different than thedistance between the first gear and the second gear, such that the rackcan only alternately engage the first length with the first gear or thesecond length with the reversing gear.
 6. The device of claim 2, whereinthe rack is moveable back and forth along a first axis parallel to thedrive shaft axis to alternately engage one of the first gear and thereversing gear, and wherein the rack is moveable back and forth along asecond axis parallel to the deployment axis to rotate one of the firstgear and the reversing gear when alternately engaged therewith.
 7. Thedevice of claim 6, wherein the rack includes a trigger extending outsideof the handle, the trigger engageable by a user to move the rack alongthe second axis, wherein movement of the rack along the second axis in aproximal direction when engaging the first gear translates to movementof the deployment member in the second direction, and wherein movementof the rack along the second axis in a proximal direction when engagingthe reversing gear translates to movement of the deployment member inthe first direction.
 8. The device of claim 7, wherein the trigger has astarting position and the deployment assembly further comprises one ormore springs cooperatively engaged with the rack to apply a biasingforce onto the rack to return the trigger to the starting position. 9.The device of claim 1, wherein translating the elongate deploymentmember in the first direction at least partially deploys the stent fromwithin the sheath.
 10. The device of claim 6, wherein the rack ismoveable in the proximal direction along the second axis a predeterminedstroke length.
 11. The device of claim 10, wherein the stroke length isless than the length of the stent.
 12. A system for controlled stentdelivery comprising: a self-expanding stent; an elongate inner memberhaving a proximal end and a distal end, the inner member disposed distalto the handle and configured to extend within a lumen of the stent: aconstraining sheath having a proximal end and a distal end, the sheathextending about the inner member and operable with the inner member toconstrain the stent therebetween; and a handle containing a deploymentassembly, the deployment assembly comprising: an elongate deploymentmember having a proximal end, a distal end, and a deployment axisextending therealong, the distal end of the deployment member connectedto a proximal end of the constraining sheath, wherein the assembly isoperable to translate the deployment member in incremental steps alongthe deployment axis in a first direction to at least partially deploythe stent, and is operable to translate the deployment member inincremental steps along the deployment axis in a second direction to atleast partially constrain the stent.
 13. The system of claim 12, whereinthe deployment assembly further comprises: a drive gear configured toengage the elongate deployment member; a drive shaft, having a driveshaft axis perpendicular to the deployment axis, the drive shaft axiallydisposed through and coupled to the drive gear; a first gear axiallydisposed about and coupled to the drive shaft; a second gear axiallydisposed about and coupled to the drive shaft, the second gear spacedapart from the first gear along the drive shaft axis; a reversing gearin communication with the second gear; a rack configured to alternatelyengage the first gear and the reversing gear; and a trigger configuredto translate the rack proximally and distally.
 14. The system of claim13, further comprising: a first one-way bearing coupled to the firstgear and axially disposed about and coupled to the drive shaft, thefirst bearing configured to prevent the first gear from imparting arotary motion to the drive shaft that translates the deployment memberin the first direction; and a second one-way bearing coupled to thesecond gear and axially disposed about and coupled to the drive shaft,the second bearing configured to prevent the second gear from impartinga rotary motion to the drive shaft that translates the deployment memberin the second direction.
 15. The system of claim 13, wherein the rack ismoveable back and forth along a first axis parallel to the drive shaftaxis to alternately engage one of the first gear and the reversing gear,and wherein the rack is moveable back and forth along a second axisparallel to the deployment axis to rotate one of the first gear and thereversing gear when alternately engaged therewith.
 16. The system ofclaim 15, wherein the rack is moveable in the proximal direction alongthe second axis a predetermined stroke length.
 17. A method ofdelivering a stent comprising: inserting a stent into a patient to adeployment location, the stent disposed on an inner member andconstrained within a sheath, the sheath having a proximal end connectedto an end of an elongate deployment member, the deployment memberextending along a deployment axis; and at least partially retracting thesheath proximally from about the stent in incremental strokes, whichcorresponds to proximal movement of the deployment member along thedeployment axis, wherein a single stroke retracts the sheath a distanceless than a length of the stent.
 18. The method of claim 17, whereinretracting the sheath from about the stent further comprises moving arack proximally along an axis parallel to the deployment axis, andwherein the rack communicates with one or more gears to transfer theproximal movement of the rack, through rotation of the gears, to theproximal movement of the deployment member.
 19. The method of claim 18,further comprising at least partially reconstraining the stent withinthe sheath in incremental strokes, which correspond to a distal movementof the deployment member along the deployment axis, wherein a singlestroke reconstrains the stent within the sheath a distance less than alength of the stent.
 20. The method of claim 19, wherein reconstrainingthe stent within the sheath further comprises moving a rack proximallyalong the axis parallel to the deployment axis, and wherein the rackcommunicates with one or more gears to transfer the proximal movement ofthe rack, through rotation of the gears, to the distal movement of thedeployment member.